Automatic balancer for rotating bodies.



M. LEBLANC. AUTOMATIC BALANCER FOR ROTATING BODIES.

APPLICATION FILED DEC. 1. I913.

Patented Nov. 2, 1915.

T VzZ/wsses I following is a specification.

l 'ocll'w h om z't may-concern. I. I -Be it known that I, MAURICELnBLANqacitizen of the Republicof' France, residing in Paris, France,have invented certain new and useful Improvements 1n Automatlc Balancersfor Rotating" Bodies, of 'which the When it is required that a rotor Ishould rotate very rapidly, it is necessarythatrits geometric axisshould coincide very approximately with one of its principal axes vofinertia through its center of gravity, which axis is called simply itsaxis of inertia in the following description; If this condition is notfulfilled, if the rotorshaft'is rigid and its bearings fixed, the rotorrotates around its axis of symmetry, but exerts strong reactions on itspoints of supports. If the rotor shaft is flexible and rests in fixedbearings, or if the shaft is rigid and the bearings movable, I or if acombination of these two conditions occurs, the rotor insead of rotatingaround its geometric axis, rotates around its axis of inertia, or atleast around an axis very near to the latter. In these conditions thereis no strong reaction on the points of support, but

the shaft whirls according to the'o'rdinary expression, whichconsequently strains the parts attached to the rotating members. Alsothe rotor should generally rotate with a small amount of clearancewithin the stator; to avoid rubbing contacts, in spite of the whirlingaction," it is necessary to in crease the clearance and this is oftendisad: vantageous.

The axis of inertia can bebrought into coincidence with the geometricaxis by attaching at the ends of the shaft two masses, the positions ofwhose centers of gravity are carefully arranged. Two additional massesare suflic'ient, but if a rotor comprises several wheels, it ispreferable to first adjust the I E. B ANO, err 431s, rnAN cE."

. Atrromrrc BALANCE gong-ROTATING IE Specification of Letters Batent.,;1

centrifugal forces during the rOta'tiOIL In m applicationNo. 711,177,fi1ed' July p 23, 1912 I-"have described and claimed baljancerscomprising-masses-secured' to the .rotor shaft and h'avingla-circularchannel for each balancer, and a dense, material,,the

particles of which are mobile, partly filling, 1

the said channels,"by-means of which the "geometric axes of the rotorand the prin- 'cipalaxes of inertia ,are automati'call brought into atleast approximate coincidence; and in said application I haveillustrated severalspecific forms of such an ap- 'paratus. The presentapplication isbased uponone of the specific forms illustrated in theaforesaid application.

The accompanying drawings illustrate an embodiment of the presentinvention, Figure 1 being an axial section; Fig. 2 a transverse sectionon the line wa2 in Fig. 1.

-Referring to the construction illustrated, the shaft A which is to bebalanced carries a flywheel G upon which is shrunk a rim B provided withan internal groove 1) which forms an annular channel around theflywheel. ,A certain quantity of mercury or other mobile material isintroduced through relatively to thatof the rotor.

The particular point of the present appli cation is the damping of anyoscillatory movements of the mercury which might occur by reason ofitsacquiring a velocity different from that of the walls of the annularpassage. For this purpose dampers h rat ntednomaieisg Application filedDecember 1,1913. sea amm. 1

'holes D, after which the remainder of the I annular passage may befilled with a viscous of various sorts may be used. I prefer sheetiron-plates a placed at equal intervals in grooves 12' at the sides ofthe annular passage, .so that said plates a extend transversely acrossthe passage. Each of these plates a has a small opening 0' near itsouter edge, and another larger openin (1 near its inner edge. Themercury ows from one compartment to another through openings 0'', whilethe flywheel is rotating and while the mass of mercury is seeking itsposition of equilibrium. The air or viscous material which fills thesurplus space in the annular compartment can pass easily through thelarger openings d along the inner edges of the damping plates.

The smaller the openings 0 the more damped are the movements of themercury with relation to the walls of the annular passage. At the sametime if the openings 0 were made too small the sensitiveness of theapparatus would be diminished; in case of accident, the flow of mercuryfrom one position of equilibrium to another might take too long.

It is necessary to take into consideration the effects due tocapillarity and surface tension. There should be sufficient mercury ineach compartment to cover the small open ings 0'. If one compartmentwere full and an adjacent compartment empty, the mercury in flowing fromthe former to the latter through a very small hole, would meet with avery large resistance due to capillarity. To overcome this, considerablepressure must be developed by centrifugal force at the position of theopening and this requires a high speed in the balancer. Until thisoccurs the action may be very irregular. This drawback can be avoidedwith certainty, if there is sufficient mercury to fill all thecompartments but one.

It is also necessary that the minimum thickness of the mercury ring whenit has been displaced by the rotation, so that the axis of the freesurface does not coincide with the geometric axis, should not be toosmall, or otherwise the surface tension would prevent the mercury fromtaking up its position freely. For this reason it is convenient that themercury should almost com pletely fill the ring, that is that the volumeof the layer of air or oil on the surface of the mercury should bealways small compared to the volume of the latter.

Though I have described with great particularity of detail a specificembodiment of my invention, yet it .is not to be understood that theinvention is restricted to the par ticular embodiment described. Variousmodifications thereof in detail and in the arrangement and combinationof the parts may be made by those skilled in the art with out departingfrom the invention as defined in the following claims.

What I claim is 1. Balancers for a rotor which is capable of rotationabout a principal axis of inertia through its center of gravity, saidbalancers comprising masses secured to the rotor shaft and having acircular channel for each halancer, and a dense material in saidchannel, the particles of which are mobile, and means for damping themotion of said material relatively to the walls of the channelcontalning it.

2. Balancersfor a rotor which is capable of rotation about a principalaxis of inertia through its center of gravity, said balancers comprisingmasses secured to the rotor shaft and having a circular channel for eachbalancer, and a dense material in said channel the particles of whichare mobile, and plates arranged transversely across said channel andprovided with apertures permitting a damped movement of said materialrelatively to the walls of the channel containing it.

3. Balancers for a rotor which is capable of rotation about a principalaxis of inertia through its center of gravity, said balancers comprisingmasses secured to the rotor shaft and having a circular channel for eachbalancer, a heavy liquid in said channel, and means for damping themovement of said liquid relatively to the walls of the channelcontaining it.

4. Balancers for a rotor which is capable of rotation about a principalaxis of inertia through its center of gravity, said balancers comprisingmasses secured to the rotor shaft and having a circular channel for eachbalancer, a heavy liquid in said channel, and plates arrangedtransversely across said channel and provided with small aperturespermitting a damped movement of said ma terial relatively to the wallsof the channel containing it.

In witness whereof, I have hereunto signed my name 1n the presence oftwo subscribing witnesses.

-MAURIGE LEBLANG.

Witnesses:

HANSON C. Coxn, GABRIEL BELLIARD.

